Obitsu River
river in Japan
The Obitsu River (小櫃川, Obitsu-gawa) is a river in Kimitsu, Kisarazu, and Sodegaura, Chiba Prefecture, Japan. The river is 88 kilometers (55 mi) in length and has a drainage area of 273.2 square kilometers (105.5 sq mi).
Description
The Obitsu emerges from the densely forested valleys around Mount Motokiyosumi (344 meters (1,129 ft)) in the Bōsō Hill Range and empties into Tokyo Bay. It is the second largest river in Chiba Prefecture after the Tone River (322 kilometers (200 mi)). The upper reaches of the Obitsu meander through Kimitsu, the middle of the river runs more directly through Kisarazu, and the lower reaches form and estuary and a triangular delta in Sodegaura, an area known as the Banzu Tidal Flats. The Obitsu then turns briefly west back into Kisarazu to empty into Tokyo Bay. The tidal flats of the Obitsu host numerous species of birds and crustaceans. In 2012 an IUCN Red List endangered species crab, Uca lactea lactea, was discovered at the mouth of the river, and may be the northernmost habitat of the crab in Japan.
The Koito River, similarly to the Obitsu, emerges from Mount Motokiyosumi, flows east across Bōsō Peninsula, and empties into Tokyo Bay. The two rivers are the longest in the western region of the peninsula.
This brief starts where responsible research should: with the source description of “Obitsu River” as river in Japan. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the places & architecture register because the source frames it as river in Japan. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Place names and jurisdictional language are key evidence: both can reveal earlier catalogue descriptions and overlooked record series. The source revision retrieved here is dated Sep 4, 2026. The linked authority identifier is Q7074982. The first chronological checks are 2012.
Modern boundaries and familiar names can conceal earlier jurisdictions or structures that do not align with the present site. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
- Jurisdictional context
- Routes into maps and plans
Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
- Establish the record: confirm the title “Obitsu River”, its source revision and the description used here.
- Expand the search: follow Obitsu River primary sources, Obitsu River archive and Obitsu research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Obitsu River”?
- Which authority defined the place, boundary or structure at the relevant date?
- What physical evidence or contemporary plan supports the description?
Search terms from this dossier
This entry incorporates text from “Obitsu River” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.